Monday

Scientists Have Discovered That Mantis Shrimps Learn And Remember Like Insects

Thinking like an insect might sound like an insult to a creature that possesses one of the most sophisticated eyes in the animal kingdom: That is what most people would think after reading this post's title. However, being able to learn and remember things like insects do is actually a good thing for the mantis shrimp.

A new scientific study, which was published in eLife on September 26 2017, uncovered that the brains of mantis shrimps contain learning and memory centers that so far have been observed only in insects.

Mantis shrimps are marine crustaceans that can grow up to 38 cm in length. What is so special about these creatures is that they have two super powers: Superb eyes and deadly claws. Their eyes contain up to 16 photoreceptors that allow them to see even ultraviolet light. Compared to the human eye which has only three photoreceptors, the mantis shrimp eye surely look like an over-engineered product of evolution. As if those eyes weren't enough, mantis shrimps have extremely powerful appendages which they use to attack their preys with a spring-like motion. With an attacking force similar to that of a bullet fired from a 22 caliber gun, they can even break through acquarium glass.

Now that we have properly introduced the mantis shrimp, it is time to give it another "compliment": The research paper entitled "An insect-like mushroom body in a crustacean brain", showed that contrary to what was previously thought, mantis shrimps' brains contain memory and learning centers, called mushroom bodies. Those mushroom bodies were previously only seen in insects. Essentially, mantis shrimps belong to the arthropod group that encompasses more than four million species. All arthropods, including crustaceans, evolved from a common ancestor that lived more than 550 million years ago. What's more, crustaceans which themselves evolved from one of the two branches of the arthropod family, split again to give rise to an offshoot that would later become what we know today as insects.

The findings suggest that mushrooms bodies, which play a central role in forming and storing memories in insects, are actually ancient structures that may have stemmed from a common ancestor of crustaceans and insects. Mantis shrimps, unlike their close relatives, likely retained their mushroom bodies due the fact that they hunt over large distances, a behavior which would require them to develop a complex memory system to analyse their environment. This may explain why mantis shrimps, more than any other crustacean species, exhibit complex behavior that requires spatial memory and visual recognition capabilities similar to those found in insects.